High density mounting of electronic components on printed circuit boards and other substrates is common in the electronics industry. Miniature ceramic surface mount type capacitors having multiple layers have been used for some time in electronic devices such as cellular telephones, network routers, computers, and the like. The manufacturing techniques of such devices must be precise to provide for the greatly reduced size of these devices, while still affording desirable electrical operating characteristics.
More recently it has become desirable to provide further types of components and various sub-circuits in on-board mountable form. Several United States Patents are directed to various aspects of electronic component manufacture and mounting techniques. For example, commonly owned U.S. Pat. No. 5,889,445 (Ritter et al., entitled “Multilayer Ceramic RC Device”) discloses RC devices which include a plurality of first and second ceramic layers interleaved to form a stack. The ceramic layers each include a suitable electrode structure of opposite polarity forming the equivalent of multiple two-plate capacitors. Known embodiments of multilayer ceramic capacitors (MLCC's) are also shown, for example, in FIGS. 2 and 3 of commonly owned U.S. Pat. No. 7,352,563 (Pelcak et al., entitled “Capacitor assembly”).
The diversity of modern technical applications creates a need for efficient electronic components and integrated circuits for use therein. Capacitors are a fundamental component used for filtering, decoupling, bypassing and other aspects of such modern applications which may include wireless communications, high-speed processing, networking, circuit switching and many other applications. Dramatic increases in the speed and packing density of integrated circuits has resulted in advancements in decoupling capacitor technology.
When high-capacitance decoupling capacitors are subjected to the high frequencies of many present applications, performance characteristics become increasingly more important. Since capacitors are fundamental to such a wide variety of applications, their precision and efficiency is imperative. Many specific aspects of capacitor design have thus been a focus for improving the performance characteristics of capacitors.
A wide variety of conventional capacitors are available on the market today, and each provides a unique combination of performance characteristics well-suited for particular applications. For example, multilayer ceramic capacitors (MLCCs) are typically quite effective for frequency filtering applications. It is quite common that these and other particular capacitor types will be used in a single integrated circuit environment. In such instances, the different capacitors may be connected, for example, in parallel on a printed circuit board (PCB) as discrete components. Such approach may require a relatively large amount of circuit space and separate mounting pads for each capacitor.
For some time, the design of various electronic components has been driven by a general industry trend toward miniaturization and ease of incorporation of components into new or existing applications. In such regard, a need exists for smaller electronic components having exceptional operating characteristics. For example, some applications require the use of passive devices exhibiting various characteristics including capacitive, inductive, and/or resistive characteristics or combination assemblies thereof, but are severely limited in the amount of space (known as “real estate”) such devices may occupy on a circuit board. It is important that such devices or combinations be configured for maximum ease of physical and electrical attachment to such circuit boards while occupying the least amount of “real estate” possible. As a result, efforts continue to strive for component miniaturization, orientation efficiency and other ways to save space and maximize board real estate in a PCB environment.
It may also be desirable to improve other capacitor performance characteristics, such as ESR (Equivalent Series Resistance), which is the inherent resistance value of a capacitor.
Another capacitor characteristic that may affect circuit applications is piezoelectric noise or electro-mechanical or acoustic noise, which is prevalent in many mounted MLCC applications. Low level piezoelectric noise may be generated, for example, when the capacitor ceramics are subjected to alternate voltages, which can cause mechanical vibrations in the capacitor. The inherent nature of the ceramic material converts the mechanical vibrations to generally low-level electrical noise. Significant amounts of piezoelectric noise can have an effect on signal quality, especially in high frequency applications. As such, it is often desirable to reduce piezoelectric noise levels in circuit applications.
Capacitors deform in response to applied voltage (electric field) due to electrostrictive behavior inherent in all dielectric materials, as expressed by the following known equation:Strain=Mij*Electric Field2 
In general, high dielectric constant materials have high electrostrictive coefficients. A CV (capacitance times voltage) rating is related in part to the volumetric efficiency of a capacitor. In general, the higher the capacitance, the larger the volume of the capacitor. Given some capacitance value, the higher the voltage rating, the larger the volume of the capacitor. Thus, when a capacitor has a “high CV rating”, that means that it is volumetrically efficient, and offers a small physical size compared to other capacitor types. High CV capacitors have evolved to have very thin internal layers, giving very high electric field strength even at modest operating voltage.
Mechanical strain (vibrations) may be transferred from the capacitor through the solder terminals to PCB substrates. The capacitor acts as a driver, in essence, a drum stick, while the PCB behaves as a sounding instrument, such as a drum head. Therefore, the predominant audible noise is generated by vibrations from the PCB, not the capacitor itself.
A converse effect, that is, vibrations on PCB coupled through terminals to the capacitor, can also cause an AC-ripple voltage on the capacitor. Such an effect is called “microphonics” and can be a problem in special cases.
Various approaches have been previously provided in attempts to reduce electro-mechanical noise associated with mounted MLCC devices, and include such as minimizing solder amount (for mounting of device onto a PCB), turning the orientation of MLCC internal layers parallel to PCB, using lower K dielectric materials, increasing stand-off (leads), pre-mounting capacitors on substrate, increasing clamping force (for providing larger inactive margins), and simply replacing the MLCC devices with a different type of device such as a tantalum capacitor. Such approaches inherently involve various tradeoffs, for example, in some instances, increased costs or increased complexity of MLCC device designs or mounting techniques.
Additional patent citations include U.S. Pat. No. 5,629,578 (Winzer et al., entitled “Integrated composite acoustic transducer array”), related to a multilayer structure which has associated noise cancellation features, and U.S. Pat. No. 8,665,059 (Korony et al., entitled “High Frequency Resistor”), related to a resistor having flexible termination material. See, also, Korony U.S. Application Publication No. 2011/0090665 entitled “Thin Film Surface Mount Components” and Hattori U.S. Application Publication Nos. 2014/0016242 entitled “Electronic Component”, 2013/0299224 entitled “Ceramic Electronic Component and Electronic Device”, and 2013/0284507 entitled “Electronic Component.”
The presently disclosed subject matter relates generally to small electronic components adapted to be surface mounted on a larger circuit board. More particularly, the subject matter may relate to a surface mount capacitor device for use in a variety of applications. According to industry practice, the size of a surface mount component is generally expressed as a number “XXYY,” with XX and YY being the length and width, respectively, in hundredths of an inch.
While various implementations of capacitor devices and associated assemblies and mounting methodologies therefor have been developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.